Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss.

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

Dental Caries, Race and Incident Ischemic Stroke, Coronary Heart Disease, and Death.

BACKGROUND: Dental caries is a highly prevalent disease worldwide. In the United States, untreated dental caries is present in >1 in 5 adults. The objective of this study was to determine the relationship between dental caries and incident ischemic stroke, coronary heart disease (CHD) events, and death. METHODS: The dental cohort (n=6351) of the ARIC study (Atherosclerosis Risk in Communities) was followed for incident ischemic stroke, CHD event, and all-cause mortality. Of all the participants at visit 4 (n=11 656), those who were unable to go through dental examination, or with prevalent ischemic stroke and CHD events, were excluded. The full-mouth dental examination was conducted at visit 4 (1996-1998), assessing dental caries. The dose response of decayed, missing, and filled surfaces due to caries was assessed and related to the outcome. Outcomes were assessed through the end of 2019. Additionally, the effect of regular dental care utilization on dental caries was evaluated. RESULTS: Participants with ≥1 dental caries had an increased risk of stroke (adjusted hazard ratio [HR], 1.40 [95% CI, 1.10-1.79]) and death (adjusted HR, 1.13 [95% CI, 1.01-1.26]) but not for CHD events (adjusted HR, 1.13 [95% CI, 0.93-1.37]). The association of dental caries and ischemic incident stroke was significantly higher in the African American population compared with the White subgroup (interaction term P=0.0001). Increasing decayed, missing, and filled surfaces were significantly associated with stroke (adjusted HR, 1.006 [95% CI, 1.001-1.011]) and death (adjusted HR, 1.003 [95% CI, 1.001-1.005]) but not CHD (adjusted HR, 1.002 [95% CI, 1.000-1.005]). Regular dental care utilization lowered (adjusted odds ratio, 0.19 [95% CI, 0.16-0.22]; P<0.001) the chance of caries. CONCLUSIONS: Among the cohort, dental caries was independently associated with the risk of ischemic stroke and death, with the effect higher in African American participants. Regular dental care utilization was associated with a lower chance of caries, emphasizing its relevance in the prevention of these events.

Association of Dental Infections with Intracranial Atherosclerotic Stenosis.

INTRODUCTION: Periodontal disease (PD) and dental caries are oral infections leading to tooth loss that are associated with atherosclerosis and cerebrovascular disease. We assessed the hypothesis that PD and caries are associated with asymptomatic intracranial atherosclerosis (ICAS) in the Atherosclerosis Risk in Communities (ARIC) study. METHODS: Full-mouth clinical periodontal measurements (7 indices) collected at 6 sites per tooth from 6,155 subjects from the Dental Atherosclerosis Risk in Communities Study (DARIC) without prior stroke were used to differentiate seven PD stages (Periodontal Profile Class [PPC]-I to -VII) and dental caries on coronal dental surface (DS) and dental root surface (DRS). A stratified subset underwent 3D time-of-flight MR angiogram and 3D high isotropic-resolution black blood MRI. ICAS was graded according to the criteria established by the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial. We evaluated the relationship between PD stage and dental caries with asymptomatic ICAS, graded as no ICAS, <50% ICAS, and ≥50% ICAS. RESULTS: Among dentate subjects who underwent vascular imaging, 801 (70%) had no ICAS, 232 (20%) had <50% ICAS, and 112 (10%) had ≥50% ICAS. Compared to participants without gum disease (PPC-I), participants with mild-moderate tooth loss (PPC-VI), severe tooth loss (PPC-VII), and severe PD (PPC-IV) had higher odds of having <50% ICAS. Participants with extensive gingivitis (PPC-V) had significantly higher odds of having ≥50% ICAS. This association remained significant after adjusting for confounding variables: age, gender, race, hypertension, diabetes, dyslipidemia, 3-level education, and smoking status. There was no association between dental caries (DS and DRS) and ICAS <50% and ≥50%. CONCLUSION: We report significant associations between mild-moderate tooth loss, severe tooth loss, and severe PD with <50% ICAS as well as an association between extensive gingivitis and ≥50% ICAS. We did not find an association between dental caries and ICAS.

Dental Caries a Risk Factor for Intracerebral Hemorrhage.

INTRODUCTION: Streptococcus mutans is a known cause of dental caries that contains a collagen-binding protein, Cnm, and exhibits inhibition of platelet aggregation and matrix metalloproteinase-9 activation. This strain has been linked to aggravation of experimental intracerebral hemorrhage (ICH) and may be a risk factor for ICH. The purpose of this study was to test the association between dental caries and incident ICH. METHODS: The presence of dental caries and periodontal disease was assessed in subjects from the Dental Atherosclerosis Risk in Communities (DARIC) study without prior stroke or ICH. This cohort was followed for incident ICH over a period of 10 years. Cox regression was used to compute crude and adjusted hazards ratio from the dental assessment. RESULTS: Among 6,315 subjects, dental surface caries and/or root caries were recorded in 1,338 (27%) subjects. Of those, 7 (0.5%) had incident ICH over a period of 10 years following the visit 4 assessment. Of the remaining 4,977 subjects, 10 (0.2%) had incident ICH. Those with dental caries versus those without dental caries were slightly younger (mean age 62.0 ± 5.7 vs. 62.4 ± 5.6, p = 0.012), had a greater proportion of males (51 vs. 44%, p < 0.001), African Americans (44 vs. 10%, p < 0.001), and were hypertensive (42 vs. 31%, p < 0.001). The association between caries and ICH was significant (crude HR 2.69, 95% CI 1.02-7.06) and strengthened after adjustment for age, gender, race, education level, hypertension, and periodontal disease (adjusted HR 3.88, 95% CI 1.34-11.24). CONCLUSION: Dental caries is a potential risk for incident ICH after caries detection. Future studies are needed to determine if treatment of dental caries can reduce the risk of ICH.

Periodontal Disease Treatment After Stroke or Transient Ischemic Attack: The PREMIERS Study, a Randomized Clinical Trial.

BACKGROUND: Patients with stroke/transient ischemic attack and periodontal disease (PD) are at increased risk for cardiovascular events. PD treatments that can improve stroke risk factors were tested if they might assist patients with cerebrovascular disease. METHODS: In this multicenter phase II trial, patients with stroke/transient ischemic attack and moderately severe PD were randomly assigned to intensive or standard PD treatment arms. The primary outcome measure was a composite of death, myocardial infarction, and recurrent stroke, as well as adverse events. Secondary outcome included changes in stroke risk factors. RESULTS: A total of 1209 patients with stroke/transient ischemic attack were screened, of whom 481 met the PD eligibility criteria; 280 patients were randomized to intensive arm (n=140) and standard arm (n=140). In 12-month period, primary outcome occurred in 11 (8%) in the intensive arm and 17 (12%) in the standard arm. The intensive arm was nonsuperior to the standard arm (hazard ratio, 0.65 [95% CI, 0.30-1.38]) with similar rates of adverse events (sepsis 2.1% versus 0.7%; dental bleeding 1.4% versus 0%; and infective endocarditis 0.7% versus 0%). Secondary-outcome improvements were noted in both arms with diastolic blood pressure and high-density lipoprotein cholesterol (P<0.05). CONCLUSIONS: In patients with recent stroke/transient ischemic attack and PD, intensive PD treatment was not superior to standard PD treatment in prevention of stroke/myocardial infarction/death. Fewer events were noted in the intensive arm and the 2 arms were comparable in the safety outcomes. Secondary-outcome measures showed a trend toward improvement, with significant changes noted in diastolic blood pressure and high-density lipoprotein in both the treatment arms.

Epigenome-wide association study using peripheral blood leukocytes identifies genomic regions associated with periodontal disease and edentulism in the Atherosclerosis Risk in Communities study.

AIM: To investigate individual susceptibility to periodontitis by conducting an epigenome-wide association study using peripheral blood. MATERIALS AND METHODS: We included 1077 African American and 457 European American participants of the Atherosclerosis Risk in Communities (ARIC) study who had completed a dental examination or reported being edentulous at Visit 4 and had available data on DNA methylation from Visit 2 or 3. DNA methylation levels were compared by periodontal disease severity and edentulism through discovery analyses and subsequent testing of individual CpGs. RESULTS: Our discovery analysis replicated findings from a previous study reporting a region in gene ZFP57 (6p22.1) that was significantly hypomethylated in severe periodontal disease compared with no/mild periodontal disease in European American participants. Higher methylation levels in a separate region in an unknown gene (located in Chr10: 743,992-744,958) was associated with significantly higher odds of edentulism compared with no/mild periodontal disease in African American participants. In subsequent CpG testing, four CpGs in a region previously associated with periodontitis located within HOXA4 were significantly hypermethylated in severe periodontal disease compared with no/mild periodontal disease in African American participants (odds ratio per 1 SD increase in methylation level: cg11015251: 1.28 (1.02, 1.61); cg14359292: 1.24 (1.01, 1.54); cg07317062: 1.30 (1.05, 1.61); cg08657492: 1.25 (1.01, 1.55)). CONCLUSIONS: Our study highlights epigenetic variations in ZPF57 and HOXA4 that are significantly and reproducibly associated with periodontitis. Future studies should evaluate gene regulatory mechanisms in the candidate regions of these loci.

Periodontal Disease, Atrial Fibrillation and Stroke.

BACKGROUND: We recently described the association between periodontal disease (PD) and stroke risk. PURPOSE: The purpose of this study was to test the association between PD, dental care utilization and incident atrial fibrillation (AF), as well as AF as a mediator to PD- stroke association. METHODS: In dental cohort of the Atherosclerosis Risk in Communities Study (ARIC), participants without prior AF underwent full-mouth periodontal measurements. PD was defined on an ordinal scale as healthy (referent), mild, moderate and severe. In ARIC main cohort, participants were classified as regular or episodic dental care users. These patients were followed for AF, over 17 years. Cox proportional hazards models adjusted for AF risk factors were used to study relationships between PD severity, dental care utilization and AF. Mediation analysis was used to test if AF mediated the PD- stroke association. RESULTS: In dental ARIC cohort, 5,958 were assessed without prior AF, 754 were found to have AF. Severe PD was associated with AF on both univariable (crude HR, 1.54; 95% CI, 1.26-1.87) and multivariable (adjusted HR, 1.31, 95% CI, 1.06-1.62) analyses. Mediation analysis suggested AF mediates the association between PD and stroke. In the main ARIC cohort, 9,666 participants without prior AF were assessed for dental care use, 1558 were found to have AF. Compared with episodic users, regular users had a lower risk for AF on univariable (crude HR, 0.82, 95% CI, 0.74-0.90) and multivariable (adjusted HR, 0.88, 95% CI, 0.78-0.99) analyses. CONCLUSIONS: PD is associated with AF. The association may explain the PD-stroke risk. Regular users had a lower risk of incident AF compared with episodic users.

Advances in precision oral health.

The concept of precision dentistry as it relates to precision medicine is relatively new to the field of oral health. Precision dentistry is a contemporary, multifaceted, data-driven approach to oral health care that uses individual characteristics to stratify similar patients into phenotypic groups. The objective is to provide clinicians with the information that will allow them to improve treatment planning and a patient's response to treatment. Providers that use a precision oral health approach would move away from using an "average treatment" for all patients with a particular diagnosis and move toward more specific treatments for patients within each diagnostic subgroup. Precision dentistry requires a method or a model that places each individual in a subgroup where each member is the same as every other member in relation to the disease of interest. Precision dentistry is a paradigm shift that requires a new way of thinking about diagnostic categories. This approach uses patients' risk factor data (including, but not limited to, genetic, environmental, and health behavioral), rather than expert opinion or clinical presentation alone, to redefine traditional categories of health and disease. We review aspects of current efforts to allow precision dentistry to be realized and focus on one of the major innovations that may help precision dentistry to be practiced by periodontists, the World Workshop Model. Another approach is the Periodontal Profile Class system. These two approaches represent examples of supervised and unsupervised learning systems, respectively. This review compares and contrasts these two learning systems for their ability to classify patients into homogeneous disease and risk groups, as well as their feasibility at achieving the objective of enabling precision dentistry. We conclude that: (a) the World Workshop Model concept of stages and grades works as expected, in that periodontal status appears to be more serious in each successive stage. In addition, the seriousness and the complexity of the disease are greater as the grade increases within each stage. Stages and grades are important for precision dentistry because they consider the risk of future disease and the prognosis, and enable practitioners to use more signs, symptoms, and other associated factors when placing a patient in a diagnostic category; (b) the assignment of stages and grades using unsupervised learning systems is superior to using supervised learning systems for the prediction of 10-year tooth loss and 3-year attachment loss progression. In addition, the unsupervised learning approach (Periodontal Profile Class stages) results in stronger associations between the periodontal phenotypes and systemic diseases and conditions (prevalent diabetes, C-reactive protein, and incident stroke). This probably occurs because an unsupervised learning model produces more data-driven, mutually exclusive, homogeneous groups than a supervised learning model.

Periodontal disease and incident venous thromboembolism: The Atherosclerosis Risk in Communities study.

AIM: Periodontal disease is a cardiovascular disease (CVD) risk factor but few studies have considered the relationship between periodontal disease and venous thromboembolism (VTE). We hypothesized that periodontal disease is independently associated with increased risk of incident VTE. MATERIALS AND METHODS: We used data from 8,092 participants of the Atherosclerosis Risk in Communities (ARIC) study to examine periodontal disease in 1996-1998 and incident VTE through 2011. Periodontal disease was determined using self-reported tooth loss due to gum disease and dental examinations. Cox proportional hazards regression models were used to estimate hazard ratios for VTE and 95% confidence intervals adjusted for relevant confounders. RESULTS AND CONCLUSIONS: Participants were on average 62.7 years old at baseline and 13.9% self-reported tooth loss from gum disease. Over a mean of 12.9 years of follow-up, there were 313 incident VTE events. Self-reported tooth loss due to gum disease was associated with 30% higher VTE risk (HR = 1.29 (0.96, 1.73) after adjusting demographic factors, SES, periodontal risk factors, oral hygiene, and access to dental care variables. No statistically significant associations between clinical measures of periodontitis and VTE were observed after adjustment. Further research is needed to elucidate whether a relationship between periodontal disease and VTE exists.

Biologically Defined or Biologically Informed Traits Are More Heritable Than Clinically Defined Ones: The Case of Oral and Dental Phenotypes.

The genetic basis of oral health has long been theorized, but little information exists on the heritable variance in common oral and dental disease traits explained by the human genome. We sought to add to the evidence base of heritability of oral and dental traits using high-density genotype data in a well-characterized community-based cohort of middle-age adults. We used genome-wide association (GWAS) data combined with clinical and biomarker information in the Dental Atherosclerosis Risk In Communities (ARIC) cohort. Genotypes comprised SNPs directly typed on the Affymetrix Genome-Wide Human SNP Array 6.0 chip with minor allele frequency of >5% (n = 656,292) or were imputed using HapMap II-CEU (n = 2,104,905). We investigated 30 traits including "global" [e.g., number of natural teeth (NT) and incident tooth loss], clinically defined (e.g., dental caries via the DMFS index, periodontitis via the CDC/AAP and WW17 classifications), and biologically informed (e.g., subgingival pathogen colonization and "complex" traits). Heritability (i.e., variance explained; h2) was calculated using Visscher's Genome-wide Complex Trait Analysis (GCTA), using a random-effects mixed linear model and restricted maximum likelihood (REML) regression adjusting for ancestry (10 principal components), age, and sex. Heritability estimates were modest for clinical traits-NT = 0.11 (se = 0.07), severe chronic periodontitis (CDC/AAP) = 0.22 (se = 0.19), WW17 Stage 4 vs. 1/2 = 0.15 (se = 0.11). "High gingival index" and "high red complex colonization" had h2 > 0.50, while a periodontal complex trait defined by high IL-1ß GCF expression and Aggregatibacter actinomycetemcomitans subgingival colonization had the highest h2 = 0.72 (se = 0.32). Our results indicate that all GWAS SNPs explain modest levels of the observed variance in clinical oral and dental measures. Subgingival bacterial colonization and complex phenotypes encompassing both bacterial colonization and local inflammatory response had the highest heritability, suggesting that these biologically informed traits capture aspects of the disease process and are promising targets for genomics investigations, according to the notion of precision oral health.

Periodontal Disease, Regular Dental Care Use, and Incident Ischemic Stroke.

BACKGROUND AND PURPOSE: Periodontal disease is independently associated with cardiovascular disease. Identification of periodontal disease as a risk factor for incident ischemic stroke raises the possibility that regular dental care utilization may reduce the stroke risk. METHODS: In the ARIC (Atherosclerosis Risk in Communities) study, pattern of dental visits were classified as regular or episodic dental care users. In the ancillary dental ARIC study, selected subjects from ARIC underwent fullmouth periodontal measurements collected at 6 sites per tooth and classified into 7 periodontal profile classes (PPCs). RESULTS: In the ARIC study 10 362 stroke-free participants, 584 participants had incident ischemic strokes over a 15-year period. In the dental ARIC study, 6736 dentate subjects were assessed for periodontal disease status using PPC with a total of 299 incident ischemic strokes over the 15-year period. The 7 levels of PPC showed a trend toward an increased stroke risk (χ2 trend P<0.0001); the incidence rate for ischemic stroke/1000-person years was 1.29 for PPC-A (health), 2.82 for PPC-B, 4.80 for PPC-C, 3.81 for PPC-D, 3.50 for PPC-E, 4.78 for PPC-F, and 5.03 for PPC-G (severe periodontal disease). Periodontal disease was significantly associated with cardioembolic (hazard ratio, 2.6; 95% confidence interval, 1.2-5.6) and thrombotic (hazard ratio, 2.2; 95% confidence interval, 1.3-3.8) stroke subtypes. Regular dental care utilization was associated with lower adjusted stroke risk (hazard ratio, 0.77; 95% confidence interval, 0.63-0.94). CONCLUSIONS: We confirm an independent association between periodontal disease and incident stroke risk, particularly cardioembolic and thrombotic stroke subtype. Further, we report that regular dental care utilization may lower this risk for stroke.

Genome-wide association study of biologically informed periodontal complex traits offers novel insights into the genetic basis of periodontal disease.

Genome-wide association studies (GWAS) of chronic periodontitis (CP) defined by clinical criteria alone have had modest success to-date. Here, we refine the CP phenotype by supplementing clinical data with biological intermediates of microbial burden (levels of eight periodontal pathogens) and local inflammatory response (gingival crevicular fluid IL-1ß) and derive periodontal complex traits (PCTs) via principal component analysis. PCTs were carried forward to GWAS (∼2.5 million markers) to identify PCT-associated loci among 975 European American adult participants of the Dental ARIC study. We sought to validate these findings for CP in the larger ARIC cohort (n = 821 participants with severe CP, 2031-moderate CP, 1914-healthy/mild disease) and an independent German sample including 717 aggressive periodontitis cases and 4210 controls. We identified six PCTs with distinct microbial community/IL-1ß structures, although with overlapping clinical presentations. PCT1 was characterized by a uniformly high pathogen load, whereas PCT3 and PCT5 were dominated by Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, respectively. We detected genome-wide significant signals for PCT1 (CLEC19A, TRA, GGTA2P, TM9SF2, IFI16, RBMS3), PCT4 (HPVC1) and PCT5 (SLC15A4, PKP2, SNRPN). Overall, the highlighted loci included genes associated with immune response and epithelial barrier function. With the exception of associations of BEGAIN with severe and UBE3D with moderate CP, no other loci were associated with CP in ARIC or aggressive periodontitis in the German sample. Although not associated with current clinically determined periodontal disease taxonomies, upon replication and mechanistic validation these candidate loci may highlight dysbiotic microbial community structures and altered inflammatory/immune responses underlying biological sub-types of CP.

Genome-wide association study of dental caries in the Hispanic Communities Health Study/Study of Latinos (HCHS/SOL).

Dental caries is the most common chronic disease worldwide, and exhibits profound disparities in the USA with racial and ethnic minorities experiencing disproportionate disease burden. Though heritable, the specific genes influencing risk of dental caries remain largely unknown. Therefore, we performed genome-wide association scans (GWASs) for dental caries in a population-based cohort of 12 000 Hispanic/Latino participants aged 18-74 years from the HCHS/SOL. Intra-oral examinations were used to generate two common indices of dental caries experience which were tested for association with 27.7 M genotyped or imputed single-nucleotide polymorphisms separately in the six ancestry groups. A mixed-models approach was used, which adjusted for age, sex, recruitment site, five principal components of ancestry and additional features of the sampling design. Meta-analyses were used to combine GWAS results across ancestry groups. Heritability estimates ranged from 20-53% in the six ancestry groups. The most significant association observed via meta-analysis for both phenotypes was in the region of the NAMPT gene (rs190395159; P-value = 6 × 10(-10)), which is involved in many biological processes including periodontal healing. Another significant association was observed for rs72626594 (P-value = 3 × 10(-8)) downstream of BMP7, a tooth development gene. Other associations were observed in genes lacking known or plausible roles in dental caries. In conclusion, this was the largest GWAS of dental caries, to date and was the first to target Hispanic/Latino populations. Understanding the factors influencing dental caries susceptibility may lead to improvements in prediction, prevention and disease management, which may ultimately reduce the disparities in oral health across racial, ethnic and socioeconomic strata.

A new way to estimate disease prevalence from random partial-mouth samples.

AIM: Standard partial-mouth estimators of chronic periodontitis (CP) that define an individual's disease status solely in terms of selected sites underestimate prevalence. This study proposes an improved prevalence estimator based on randomly sampled sites and evaluates its accuracy in a well-characterized population cohort. METHODS: Importantly, this method does not require determination of disease status at the individual level. Instead, it uses a statistical distributional approach to derive a prevalence formula from randomly selected periodontal sites. The approach applies the conditional linear family of distributions for correlated binary data (i.e. the presence or absence of disease at sites within a mouth) with two simple working assumptions: (i) the probability of having disease is the same across all sites; and (ii) the correlation of disease status is the same for all pairs of sites within the mouth. RESULTS: Using oral examination data from 6793 participants in the Arteriolosclerosis Risk in Communities study, the new formula yields CP prevalence estimates that are much closer than standard partial mouth estimates to full mouth estimates. CONCLUSIONS: Resampling of the cohort shows that the proposed estimators give good precision and accuracy for as few as six tooth sites sampled per individual.

A 24-month evaluation of a percutaneous osseointegrated limb-skin interface in an ovine amputation model.

Percutaneous osseointegrated (OI) prostheses directly connect an artificial limb to the residual appendicular skeleton via a permanently implanted endoprosthesis with a bridging connector that protrudes through the skin. The resulting stoma produces unique medical and biological challenges. Previously, a study using a large animal amputation model indicated that infection could be largely prevented, for at least a 12-month period, but the terminal epithelium continued to downgrow. The current study was undertaken to test the longer-term efficacy of this implant construct to maintain a stable skin-implant interface for 24 months. Using the previously successful amputation and implantation surgical procedure, a total of eight sheep were fitted with a percutaneous OI prosthesis. Two animals were removed from the study due to early complications. Of the remaining six sheep, one (16.7%) became infected at 15-months post-implantation and five remained infection-free for the intended 24 months. The histological data of the remaining animals further confirmed the grossly observable epithelial downgrowth. Albeit a receding interface, it was clear that all animals that survived to the end of the study had residual fibrous soft-tissue ingrowth into, and debris within, the exposed titanium porous-coated surface. Overall, the data demonstrated that the porous coated subdermal barrier offered initial protection against infection. However, the fibrous skin attachment was continuously lysed over time by the down-growing epithelium.

Cluster adjusted regression for displaced subject data (CARDS): Marginal inference under potentially informative temporal cluster size profiles.

Ignorance of the mechanisms responsible for the availability of information presents an unusual problem for analysts. It is often the case that the availability of information is dependent on the outcome. In the analysis of cluster data we say that a condition for informative cluster size (ICS) exists when the inference drawn from analysis of hypothetical balanced data varies from that of inference drawn on observed data. Much work has been done in order to address the analysis of clustered data with informative cluster size; examples include Inverse Probability Weighting (IPW), Cluster Weighted Generalized Estimating Equations (CWGEE), and Doubly Weighted Generalized Estimating Equations (DWGEE). When cluster size changes with time, i.e., the data set possess temporally varying cluster sizes (TVCS), these methods may produce biased inference for the underlying marginal distribution of interest. We propose a new marginalization that may be appropriate for addressing clustered longitudinal data with TVCS. The principal motivation for our present work is to analyze the periodontal data collected by Beck et al. (1997, Journal of Periodontal Research 6, 497-505). Longitudinal periodontal data often exhibits both ICS and TVCS as the number of teeth possessed by participants at the onset of study is not constant and teeth as well as individuals may be displaced throughout the study.

Exploring the genetic basis of chronic periodontitis: a genome-wide association study.

Chronic periodontitis (CP) is a common oral disease that confers substantial systemic inflammatory and microbial burden and is a major cause of tooth loss. Here, we present the results of a genome-wide association study of CP that was carried out in a cohort of 4504 European Americans (EA) participating in the Atherosclerosis Risk in Communities (ARIC) Study (mean age-62 years, moderate CP-43% and severe CP-17%). We detected no genome-wide significant association signals for CP; however, we found suggestive evidence of association (P < 5 × 10(-6)) for six loci, including NIN, NPY, WNT5A for severe CP and NCR2, EMR1, 10p15 for moderate CP. Three of these loci had concordant effect size and direction in an independent sample of 656 adult EA participants of the Health, Aging, and Body Composition (Health ABC) Study. Meta-analysis pooled estimates were severe CP (n = 958 versus health: n = 1909)-NPY, rs2521634 [G]: odds ratio [OR = 1.49 (95% confidence interval (CI = 1.28-1.73, P = 3.5 × 10(-7)))]; moderate CP (n = 2293)-NCR2, rs7762544 [G]: OR = 1.40 (95% CI = 1.24-1.59, P = 7.5 × 10(-8)), EMR1, rs3826782 [A]: OR = 2.01 (95% CI = 1.52-2.65, P = 8.2 × 10(-7)). Canonical pathway analysis indicated significant enrichment of nervous system signaling, cellular immune response and cytokine signaling pathways. A significant interaction of NUAK1 (rs11112872, interaction P = 2.9 × 10(-9)) with smoking in ARIC was not replicated in Health ABC, although estimates of heritable variance in severe CP explained by all single nucleotide polymorphisms increased from 18 to 52% with the inclusion of a genome-wide interaction term with smoking. These genome-wide association results provide information on multiple candidate regions and pathways for interrogation in future genetic studies of CP.

Bias in estimating the cross-sectional smoking, alcohol, obesity and diabetes associations with moderate-severe periodontitis in the Atherosclerosis Risk in Communities study: comparison of full versus partial-mouth estimates.

OBJECTIVE: To assess whether partial-mouth protocols (PRPs) result in biased estimates of the associations between smoking, alcohol, obesity and diabetes with periodontitis. METHODS: Using a sample (n = 6129) of the 1996-1998 Atherosclerosis Risk in Communities study, we used measures of probing pocket depth and clinical attachment level to identify moderate-severe periodontitis. Adjusting for confounders, unconditional binary logistic regression estimated prevalence odds ratios (POR) and 95% confidence limits. Specifically, we compared POR for smoking, alcohol, obesity and diabetes with periodontitis derived from full-mouth to those derived from 4-PRPs (Ramfjörd, National Health and Nutrition Examination survey-III, modified-NHANES-IV and 42-site-Random-site selection-method). Finally, we conducted a simple sensitivity analysis of periodontitis misclassification by changing the case definition threshold for each PRP. RESULTS: In comparison to full-mouth PORs, PRP PORs were biased in terms of magnitude and direction. Holding the full-mouth case definition at moderate-severe periodontitis and setting it at mild-moderate-severe for the PRPs did not consistently produce POR estimates that were either biased towards or away from the null in comparison to full-mouth estimates. CONCLUSIONS: Partial-mouth protocols result in misclassification of periodontitis and may bias epidemiologic measures of association. The magnitude and direction of this bias depends on choice of PRP and case definition threshold used.

Comparison of the respiratory microbiome in healthy nonsmokers and smokers.

RATIONALE: Results from 16S rDNA-encoding gene sequence-based, culture-independent techniques have led to conflicting conclusions about the composition of the lower respiratory tract microbiome. OBJECTIVES: To compare the microbiome of the upper and lower respiratory tract in healthy HIV-uninfected nonsmokers and smokers in a multicenter cohort. METHODS: Participants were nonsmokers and smokers without significant comorbidities. Oral washes and bronchoscopic alveolar lavages were collected in a standardized manner. Sequence analysis of bacterial 16S rRNA-encoding genes was performed, and the neutral model in community ecology was used to identify bacteria that were the most plausible members of a lung microbiome. MEASUREMENTS AND MAIN RESULTS: Sixty-four participants were enrolled. Most bacteria identified in the lung were also in the mouth, but specific bacteria such as Enterobacteriaceae, Haemophilus, Methylobacterium, and Ralstonia species were disproportionally represented in the lungs compared with values predicted by the neutral model. Tropheryma was also in the lung, but not the mouth. Mouth communities differed between nonsmokers and smokers in species such as Porphyromonas, Neisseria, and Gemella, but lung bacterial populations did not. CONCLUSIONS: This study is the largest to examine composition of the lower respiratory tract microbiome in healthy individuals and the first to use the neutral model to compare the lung to the mouth. Specific bacteria appear in significantly higher abundance in the lungs than would be expected if they originated from the mouth, demonstrating that the lung microbiome does not derive entirely from the mouth. The mouth microbiome differs in nonsmokers and smokers, but lung communities were not significantly altered by smoking.

Radiographic evaluation of bone adaptation adjacent to percutaneous osseointegrated prostheses in a sheep model.

BACKGROUND: Percutaneous osseointegrated prostheses (POPs) are being investigated as an alternative to conventional socket suspension and require a radiographic followup in translational studies to confirm that design objectives are being met. QUESTIONS/PURPOSES: In this 12-month animal study, we determined (1) radiographic signs of osseointegration and (2) radiographic signs of periprosthetic bone hypertrophy and resorption (adaptation) and (3) confirmed them with the histologic evidence of host bone osseointegration and adaptation around a novel, distally porous-coated titanium POP with a collar. METHODS: A POP device was designed to fit the right metacarpal bone of sheep. Amputation and implantation surgeries (n = 14) were performed, and plane-film radiographs were collected quarterly for 12 months. Radiographs were assessed for osseointegration (fixation) and bone adaptation (resorption and hypertrophy). The cortical wall and medullary canal widths were used to compute the cortical index and expressed as a percentage. Based on the cortical index changes and histologic evaluations, bone adaptation was quantified. RESULTS: Radiographic data showed signs of osseointegration including those with incomplete seating against the collar attachment. Cortical index data indicated distal cortical wall thinning if the collar was not seated distally. When implants were bound proximally, bone resorbed distally and the diaphyseal cortex hypertrophied. CONCLUSIONS: Histopathologic evidence and cortical index measurements confirmed the radiographic indications of adaptation and osseointegration. Distal bone loading, through collar attachment and porous coating, limited the distal bone resorption. CLINICAL RELEVANCE: Serial radiographic studies, in either animal models or preclinical trials for new POP devices, will help to determine which designs are likely to be safe over time and avoid implant failures.